Valve diaphragms

The diaphragm is the component that makes a diaphragm valve a diaphragm valve – and at the same time the part that wears out first. It completely separates actuator and medium, seals against the valve body and is deformed with every switching cycle. That is exactly why it is a plannable wearing part and not a failure: anyone who keeps the right replacement diaphragm in stock changes it during scheduled maintenance instead of interrupting production because of a leak. This category holds our replacement diaphragms, sorted by material and diaphragm size.

What the diaphragm does in the valve

A diaphragm valve has no stuffing box and no stem passing into the medium. The diaphragm does both jobs: it transfers the actuator force onto the weir in the valve body and at the same time seals the actuator chamber hermetically against the medium. That is why diaphragm valves are used for abrasive, solids-laden and sterile media – and why a damaged diaphragm always shows up first as external leakage or as a valve that no longer closes tightly. Complete valves are under diaphragm valves, further spare parts in valve spare parts.

The materials at a glance

The material decides which media and temperatures the diaphragm can take. EPDM is the standard for water, aqueous solutions, alkalis and steam. NBR is the material for oils, greases and fuels. FKM (also written FPM) covers acids, oils and higher temperatures but tolerates neither hot water nor strongly polar solvents. CR sits between EPDM and NBR and is weather resistant, butyl (IIR) scores with very low gas permeability. For aggressive media and ultra-pure applications there are PTFE composite diaphragms: a PTFE layer on the media side with an EPDM backing diaphragm behind it – bonded in a one-piece design or separate in a two-piece design.

Diaphragm size – the decisive dimension

The diaphragm size is the valve size, not the nominal size of the pipe. It is part of the valve type code and has to match exactly – a diaphragm of the wrong size will not seal, even if it can be inserted. In this category the sizes range from 6 to 200. If you have the type code of the valve at hand, the selection is unambiguous; if not, send us the item number of the valve and we will check it.

When to change a diaphragm

The service life of a diaphragm depends on the number of switching cycles, the medium, temperature and operating pressure and cannot be stated as a blanket figure in hours. In practice the end announces itself: the valve no longer closes cleanly, medium escapes at the top works, or the control air carries moisture. Changing a diaphragm is routine work – undo the top works, swap the diaphragm, retighten the top works crosswise to the specified torque. Because opening the valve costs far more effort than the diaphragm costs money, it pays to change it during planned downtime and to keep a set of replacement diaphragms in stock.

The series in this category

We stock 14 series with 333 versions in total. In brackets the material and the number of versions: Gemue Code 54 (PTFE/EPDM one-piece, 68), Gemue Code 17 (EPDM, 49), Gemue Code 29 (EPDM, 49), Gemue Code 5M (PTFE/EPDM two-piece, 41), Gemue Code 19 (EPDM, 38), Gemue Code 2 (NBR, 30), Gemue Code 4 (FKM, 30), Gemue Code 28 (EPDM, 8), Gemue Code 8 (CR, 6), Gemue Code 6 (butyl, 5), Gemue Code 5Q (PTFE/EPDM, 4), Gemue Code 5E (PTFE/EPDM, 2), Gemue Code 4A/4 (FKM, 2), Gemue Code 71 (PTFE/PVDF/EPDM, 1)

Your benefits with us

Worldwide shipping of all valves and measuring devices
Large stock levels for many products – current lead time available on request
Spare parts and service kits available
Fast shipping via UPS (parcel) or freight forwarder (pallets), express delivery on request
Extensive hands-on application know-how
Personal advice on selecting the right component